Nowadays, more and more electronic devices use light-emitting diodes (LEDs) as backlight. Usually, these electronic devices, such as televisions and displays, can be worked at a two-dimensional (2D) mode or a three-dimensional (3D) mode. When the electronic device is worked at the 2D mode or the 3D mode, an over-voltage protection voltage triggering the over-voltage protection is the same. However, when the electronic device is worked normally, a work voltage of the LEDs of the 2D mode is lower than that of the 3D mode. Because the over-voltage protection voltage of the 2D mode is the same as that of the 3D mode, when the work voltage of the LEDs reaches or exceeds the over-voltage protection voltage, the over-voltage protection voltage is largely greater than the normal work voltage of the LEDs of the 2D mode. Then, when the electronic device is worked at the 2D mode, the time to trigger the over-voltage protection is very long, which is easy to cause components of the electronic device to be damaged.